(1) Field of the Invention
The present invention relates generally to package sorting conveyors and, more particularly, to a conveyor system having a tiltable support, a transition zone funnel, and a secondary downstream chute.
(2) Description of the Prior Art
Conveyor systems having a number of individual carrying carts have been used for many years to carry and sort the packages or other items, such as mail. Conventional tilt tray sorters discharge their goods onto individual chutes located near each packer. For example, U.S. Pat. No. 5,054,601 to Sjogren et al. discloses a package sorting conveyor comprised of a train of tilt tray carriers coupled in tandem to form a continuous loop. Each carrier includes a pivotally mounted tilt tray normally maintained in an upright position. The carriers are moved around the loop by a series of motors spaced around the loop. Branching out from the loop are out-feed chutes or the like for receiving packages from the carriers. When a particular carrier holding a particular package to be sorted reaches a selected out-feed chute, an actuator tilts the tray to dump the package into the out-feed chute.
Another example of a similar package sorting conveyor is disclosed in International PCT Application No. PCT/DK90/00047 of Kosan Crisplant A/S.
One significant disadvantage of most conventionally designed package sorting conveyors is that the conveyor carriers laterally tilts only on a horizontal axis parallel to the direction of conveyor travel. While this accomplishes the objective of dumping the package from the carrier into an out-feed chute or the like, the package is often roughly tumbled or rolled, sometimes damaging the package's contents. One reason for this is that the package typically is unloaded from the carrier while still traveling forward at the same speed as the conveyor. Thus, packages tend to slam into a forward retaining wall of the out-feed chute before sliding down the chute.
Another problem with most conventional horizontally tilting conveyors is that because the package is moving forward at full speed when they are unloaded into the out-feed chute, the out-feed chute must be relatively wide so that the package does not miss the chute and fall off the conveyor past the chute. This often unnecessarily decreases the number and location of the discharge chutes of the conveyor system.
U.S. Pat. Nos. 4,744,454 and 5,086,905, both to Polling, disclose previous attempts to remedy this problem of rough handling by conventional laterally tilting conveyor carriers. Both of these patents to Polling disclose a conveyor element for a package conveyor that includes a tilting carrier tray mounted to be rotatably about two swivel axis. A first swivel shaft extends obliquely downward from the under side of the carrying tray and is in turn connected at an angle to the end of a second swivel shaft extending obliquely upwards from a base support part of the conveyor element. Together, the two swivel shafts form a "V" that points in the direction of the conveyor travel. Both of the swivel shafts lie in the vertical plain of symmetry of the conveyor element when the carrier tray is disposed in its upright position.
Because the carrier tray of Polling rotates about two oblique axis, the carrier tray tilts not only on a horizontal axis, but is moved through a geometrically complex spatial reorientation during package discharge. This allows for more gentle placement of a package on an out-feed chute than can be accomplished using conventional conveyor trays that laterally tip only on a horizontal axis because the Polling conveyor element imparts some degree of rearward velocity to the package as it is discharged, which, when added to the forward velocity of the conveyor system, results in the package's forward velocity during discharge being lessened.
However, the conveyor elements of both of Polling's patents are unduly complicated. In fact, the second Polling patent was directed towards simplifying the original design disclosed in the first Polling patent which was expensive and complicated to manufacture efficiently. As a result of this complexity and cost, the Polling devices have not enjoyed significant commercial acceptance and success. In addition, there is no provision in Polling to take advantage of the tilting movement of the tray to allow the direction of the discharged package to be further controlled.
Thus, there remains a need for a new and improved tilt tray system which provides two-axis tilting and discharge while, at the same time, further controls the direction of the discharged package to permit the package to be placed at whatever location is desired.